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Chainsaw Porting Theory

Mastermind

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A lot of guys ask me why we choose the port timing numbers we do.....or why we would want to lower an exhaust port, when all the two stroke tuners books clearly say a higher exhaust will provide more horsepower....

Let's kick some of these things around......

Questions?
 

idiotwithasaw

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pud

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Im always curious to know how u decide what way to go when u run a stock saw , for example this saw needs more intake or higher transfers ? Is it traits that u pick up on from running lots of saws and studying them and a lot of trial and error ... Lower exhaust makes sense to me , longer stroke build more compression ect
 

smokey7

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Awesome I am following closely.
 

Moparmyway

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Im always curious to know how u decide what way to go when u run a stock saw , for example this saw needs more intake or higher transfers ? Is it traits that u pick up on from running lots of saws and studying them and a lot of trial and error ... Lower exhaust makes sense to me , longer stroke build more compression ect

I'd say its about 40% traits from running lots of saws after the 60% of trial and errors

The best way to answer most porting questions is to be saw specific, as what works with one saw does not necessarily work with another saw.
Yes, some theories do apply to all saws, but the best way to see what works is to change one thing, then run the saw.
If you gain, make a note and keep going ........... if you lose, chalk it up, make a note, and dont go further in that one area

Just because Homer Simpson hogs out his lower transferrs does not mean that everyone should do the same thing. Homer might be doing other things to the motor that allow the lowers to respond better to being hogged out

Here is where the rubber meets the road .................the more you know about 2 strokes, the more you realize that you dont know squat about them.
Just when you begin to understand what youre doing, someone will come along and throw an idea at you, which makes you think that what you were origionally thinking about shouldnt or wont work.
 

quietfly

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So ill be the first to admit i know nothing about non nitro methane running 2 strokes. The little high revving whiny motors im used to porting polishing and tuning, are way different than our larger displacement wood killing ones, and im out of my comfort zone. When porting a large displacement saw like an 084, what sweet spot are you looking for?
Is it just your previous knowledge of past work that lets you know where you are and how far you can go?
 

Simondo

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A lot of guys ask me why we choose the port timing numbers we do.....or why we would want to lower an exhaust port, when all the two stroke tuners books clearly say a higher exhaust will provide more horsepower....

Let's kick some of these things around......

Questions?
Brilliant thread to start Mr M !!!
My question is based around that thing.. what sets you off in a direction with a cylinder ? Can one be looked over as to how its been designed and that would tell you how it lends its self to work and what the appropriate treatment may be along with how far you want to take things ..OR.. is it Numbers ,numbers Numbers ..first and that can start the brain a ticking. Is there a basic.. GO TO.. start point to build on. :)
 

Ray Bell

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I am always curious about the use of epoxies, jb weld, etc used to buildup/reconfigure. Does this ever come loose or fall out? Granted I have limited experience with these materials, but seems the heat and vibrations would eventually break this loose.
 

jmssaws

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I am always curious about the use of epoxies, jb weld, etc used to buildup/reconfigure. Does this ever come loose or fall out? Granted I have limited experience with these materials, but seems the heat and vibrations would eventually break this loose.
I've used jb weld for a long while and haven't had any problems. Vibration is about all that can cause trouble.
 
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